The present technology relates to an optical body, a wall member, a fitting, and a solar shading device. More particularly, the present technology relates to an optical body for diffusely reflecting incident light.
From the viewpoint of reducing an air conditioning load, there is marketed a window film for solar shading. A film for reflecting the sunlight is also marketed as one example of the solar shading technique. To produce such a film, various techniques are already disclosed which employ, as a reflecting layer, an optical multilayer film, a metal-containing film, a transparent electroconductive film, etc. (see, e.g., the pamphlet of International Publication No. 05/087680).
However, that type of reflecting layer is formed on a flat window glass, and the incident sunlight is just specularly (regularly) reflected. Therefore, the light incoming from the sky and specularly reflected by the flat window glass reaches other buildings and the ground in the nearby outdoor where the light is absorbed and converted to heat, thus raising the ambient temperature. Accordingly, a local temperature rise occurs in the surroundings of a building in which all windows are coated with the above-mentioned type of reflecting layer. This gives rise to the problems that, in urban areas, a heat island phenomenon is accelerated and grass does not grow in areas irradiated with the reflected light.